Flipper Platinum Aquarium Algae Scraper - 28"Safe for Both Glass and Acrylic Tanks! Flipper Platinum Aquarium Hand Scraper for Glass and Acrylic Tanks 28" Patent pending design allows you to use any old credit card, gift card, hotel room key etc as a scraper blade. you may never have to buy blades again! Blade cards can be inserted in any direction for multiple levels of flexibility Cut your own custom blade card shapes for cleaning difficult curved or tight areas of your tank. Solid fiberglass